In recent years, for reducing the thickness and weight of an electronic device, improving the portability of the electronic device, and preventing breakage of components in the electronic device, a housing has been required to have increased rigidity. Specifically, when the electronic device is held with one hand and operated with the other hand, when the electronic device is transported, or when a monitor or the like is opened or closed, a biased load is applied, and therefore a force acts on the housing in a torsion direction. In addition, if the electronic device is dropped by accident during transportation, a force also acts in a torsion direction. Therefore, the housing is required to have high torsional rigidity. In addition, when pressure is applied to a housing at a cramped place such as a crowded train or when an object is dropped (when a load is applied in a thickness direction), an internal electronic component or a liquid crystal component such as a display, particularly a glass member may be damaged, and therefore the housing is required to have high deflection rigidity. In view of such a background, many techniques for increasing the rigidity of a housing have been heretofore proposed.
Specifically, Patent Document 1 discloses an invention for increasing the rigidity of an electric device cabinet structure which includes a resin lower case having upper and lower electric device mounting surfaces, and an upper case having a front wall overlapping the upper electric device mounting surface. Patent Document 2 discloses an invention for increasing the rigidity of an electronic device housing by abutting the tip of a rib, which is formed on the inner surface of a first housing, against the inner surface of a second housing. Patent Document 3 discloses an invention for increasing the rigidity of an electronic device housing of by making the electronic device housing have a structure in which surfaces of two plates are selectively bonded and joined together.
In addition, in recent years, a housing has been more frequently exposed to a high-temperature environment due to heat generation associated with use in a high-temperature and high-humidity environment and sophistication of specifications of electronic components. Under such a high-temperature environment, for example, it may be unable to operate buttons due to occurrence of warpage or distortion, waterproofness may be deteriorated due to generation of gaps, or rigidity may be reduced due to detachment of a reinforcing structure, leading to impairment of functions inherent in an electronic device when the housing is formed of different materials. In view of such a background, many techniques for improving the dimensional stability of the housing have been proposed.
Specifically, Patent Document 4 discloses an invention for improving the heat dissipation property of an information processing apparatus including an outer housing to which a first case and a second case are bonded, and a metal frame disposed in the outer housing and attached to the outer housing. Patent Document 3 discloses an invention for increasing the rigidity of an electronic device housing of by making the electronic device housing have a structure in which surfaces of two plates are selectively bonded and joined together.